The invention relates generally to lasers and more specifically concerns improvements in nuclear pumped lasers.
Gaseous lasers pumped directly by charged particles from nuclear reactions, called nuclear pumped lasers, have been in existence for several years. Typical reactions used to pump the laser medium are the .sup.3 He(n,p).sup.3 H, .sup.10 B(n,.alpha.).sup.7 Li, and .sup.235 U(n,ff)FF nuclear reactions. In particular, the .sup.3 He(n,p).sup.3 H reaction has shown great promise for higher power nuclear lasers in such systems as the .sup.3 He-Ar (1.79 .mu.m). Previous nuclear pumped lasers consist of a quartz tube surrounded with polyethylene moderator and filled with .sup.3 He plus some minority species gas such as Ar, Xe or Kr. Dielectric mirrors at the ends of the tube form the optical laser cavity. When this system is exposed to a fast-neutron burst, lasing occurs at various wavelengths in Ar, Xe, or Kr. For such cylindrical systems the lasing mode volume is relatively small, and thus power output is also low.
The primary object of this invention is to effectively increase the lasing mode volume of nuclear pumped lasers and to improve the neutron coupling efficiency with the external neutron source thereby increasing the power output.
Another object of this invention is to provide means for varying the power output of a nuclear pumped laser by varying the length of the optical path through the excited lasing medium in the nuclear pumped laser.
Other objects and advantages of this invention will become apparent hereinafter and in the drawing.